An intense manhunt is underway in Turkey for a gunman who fired at a crowded Istanbul nightclub during its New Year's Eve celebrations early Sunday morning, killing at least 39 people and injuring at least another 65, said interior minister Suleyman Soylu.
Of the 39 deceased victims, five Turkish nationals have been identified so far. At least 15 foreigners were killed, but their nationalities have not yet been revealed.
Of the 69 people hospitalized, four are in critical condition and one is in very critical condition, Soylu said.
At a press conference Sunday, Soylu said the attack was carried out by only one individual. Soylu said the assailant arrived wearing a jacket and pants, and is believed to have left wearing different clothing. There were local reports that he wore a Santa Claus costume, but that has not been confirmed.
The attacker walked into Reina nightclub -- a see-and-be-seen hotspot popular with foreigners -- after midnight with a long-barreled weapon after killing a policeman and a civilian outside the venue and began spraying bullets, said Istanbul governor Vasip Sahin.
There were between 400 and 500 party-goers inside the nightclub at the time of the attack.
"Unfortunately [he] rained bullets in a very cruel and merciless way on innocent people who were there to celebrate New Year's and have fun," Sahin told reporters.
And Soylu described the attack as "as a cowardly terror attack that targeted civilians. It happened when people were renewing their hopes for the New Year. This terror attack targeted unprotected people.”
Soylu said authorities are aggressively searching for the gunman. "Our security forces have started the necessary operations. God willing he will be caught in a short period of time."
Turkish President Recep Tayyip Erdogan said in a statement Sunday, "I vehemently condemn the terror attack ... Turkey continues its combat against terror and is absolutely determined to do whatever is necessary in the region to ensure its citizens safety and peace."
The US was quick to condemn the attack.
"The President was briefed by his National Security Team on the attack in Istanbul," President Barack Obama's principal deputy press secretary Eric Schultz said in a statement. "The President expressed condolences for the innocent lives lost, directed his team to offer appropriate assistance to the Turkish authorities, as necessary, and keep him updated as warranted."
And Mark Toner, the US State Department's deputy spokesman said in a statement, "The United States strongly condemns the terrorist attack on a nightclub in Istanbul, Turkey ... We will remain in close touch with Turkish authorities throughout the investigation ... We stand in solidarity with our NATO Ally Turkey in combating the ongoing threat of terrorism."
Russian president Vladimir Putin sent Erdogan a telegram of condolences, according to the Kremlin, writing, "It is hard to imagine a more cynical crime than killing innocent people during New Year celebrations. However, terrorists don't share moral values. Our common duty is to combat terrorists' aggression," Putin said.
ABC News' Darren Reynolds, Devin Villacis and Engin Bas contributed to this report.